PTGS2 and carcinoma: In previous studies, MMP-9 expression is associated with poor prognosis in tongue and also head and neck SCCs (Juarez et al, 1993; Kawamata et al, 1998; Nyberg et al, 2002) but there is also publications where such a correlation has not been found Kim et al, 2006) However, in our bivariate analysis we observed a positive association between MMP-9 and COX-2 levels in carcinoma cells, but negative association with MMP-9 presence and high Bryne category suggesting that MMP-9 in these samples reflects, but not statistically significantly, better prognosis of the disease.